This project represents A) an ongoing joint collaborative effort, involving the WHO and other national and international biological laboratories to coordinate the collection, evaluation and interpretation of dermatoglyphic data. Specifically the objectives of this project are: 1) to establish dermatoglyphic markers in various diseases (clinical dermatoglyphics); 2) to establish the dermatoglyphic frequencies in normal control samples (control dermatoglyphics); 3) to study the distribution of dermatoglyphics among the various human populations (population dermatoglyphics); 4) to study the dermatoglyphics of the aged; 5) to study the genetics of dermatoglyphics; and, 6) to utilize dermatoglyphics as an added tool in twin diagnoses (twin dermatoglyphics). B) Evaluation of lateral functional dominance among BLSA participants. C) Cross sectional and longitudinal study of visual function BLSA participants.